Following oral ingestion, the following symptoms may be expected:
insomnia, ataxia (unsteady gait, tremor of hands, vertigo, muscle twitching), severe abdominal pain, nausea and vomiting, burning in the mouth and throat, delirium, headache, dizziness, drowsiness, bradycardia, cyanosis, miosis, pulmonary damage, epileptiform convulsions, CNS depression and coma. Inhalation of large doses of menthol may lead to dizziness, confusion, muscle weakness, nausea and double vision.
Treatment should consist of gastric lavage and aspiration. A saline purgative such as 30g of sodium sulphate in 250ml of water may be given and any convulsions controlled by intravenous diazepam.